Glazing with a rigid element optionally incorporated into an overmolded plastic

ABSTRACT

A glazing including a glazed element with at least one rigid element that may or may not be incorporated into an overmolded plastic part. The at least one rigid element has a linear thermal expansion coefficient of the same order of magnitude as that of the glazed element. Such a glazing may find, e.g., application to the addition of fixing supports or reinforcing elements to a glazing for buildings, self-propelled or towed terrestrial or marine vehicles.

The invention relates to the field of glazing and relates to glazing,particularly for buildings or motor or leisure vehicles, provided with aplastic part overmolded over the glazed element and which incorporatesor not a rigid element.

One particular example of glazing of this type in the field of landmotor vehicles is given by opening or fixed sunroofs which occupy up toalmost the entire roof area. This glazing comprises a glazed element,particularly made of toughened glass, laminated glass or transparentplastic, equipped with a plastic surround overmolded onto the glazedelement, which may incorporate rigid elements for fixing to the sunroofdrive mechanism. In order to rigidify the glazed element which, as thevehicle travels along, is subjected to deformations due to the pressureassociated with the speed of travel, it is common practice for theovermolded surround to be provided with reinforcing elements in the formof metal strips, generally made of steel.

In a technique commonly employed, the reinforcing strips areincorporated into the plastic surround directly during the overmoldingoperation by placing one or more strips as inserts with the glazedelement into the manufacturing mold and then by injecting the plastic insuch a way as to incorporate the insert or inserts.

With the temperatures at which thermoplastics are injected, or the heatgiven off by the polymerization of a two-part polyurethane using a RIM(reaction injection molding) method, which are materials and methodscommonly used for this purpose, this technique has the disadvantage ofgiving rise to deformation of the metal reinforcing elements, firstly inthe hot state by expansion in the mold, then, upon leaving the mold, bycold contraction, which deformations introduce stresses and deformationsinto the glazed element which stresses and deformations may proveinadmissible for mounting in the bodywork from a mechanical and/oresthetic point of view.

To compensate for these deformations, manufacture may be followed by astep of reshaping the glazing by compression, but this leads todeformation of the molded composite, which deformation may detract fromthe bond at the various interfaces and therefore from the integrity ofthe glazing.

A similar expansion problem may also be encountered when the vehicle issubjected to prolonged heat, particularly when parked for a long time infull sun. The alternation of heating/cooling cycles then gradually tendsto cause inevitable changes to the curve of the glazing, and thisdetracts from the line of the vehicle.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome the aforementioneddrawbacks.

To this end, the subject of the invention is glazing comprising a glazedelement with at least one rigid element which may or may not beincorporated into an overmolded plastic part, characterized in that therigid element or elements have a linear thermal expansion coefficient ofthe same order of magnitude as that of said glazed element.

By selecting, for the rigid elements according to the invention,materials which have a linear expansion coefficient similar to that ofthe glazed element, the appearance of differential expansion stresses inthe assembly formed of the glazed element, the plastic and the rigidelement(s) is avoided. As a consequence, the design and manufacture ofthe glazing area simplified, because it is no longer necessary to carryout the additional step of shaping the glazing.

Furthermore, manufacture on the whole is more reliable, because thefinal dimensions of the glazing are closer to the middle value of thepermitted tolerance range, which would not be the case with a metalelement.

In the context of the present invention, not only glass elementsconsisting of one or more sheets of glass bonded together, asappropriate, by adhesive interlayers, but also transparent ortranslucent elements made of organic material, particularly ofpolycarbonate, are termed glazed elements.

In the alternative according to the invention whereby the rigid elementor elements are not incorporated into an overmolded plastic part, theymay be connected to the glazed element, possibly with the ability ofsliding one with respect to the other, by any appropriate means such asadhesive bonding, any fixing, gripping or snap-fastening. In thisrespect, mention may be made of a rigid surround positioned around theglazed element at a relatively high shaping temperature, which contractsas it cools, snap-fastening onto the peripheral edge of the glazedelement.

As a preference, the rigid element or elements have a linear thermalexpansion coefficient differing from that of the glazed element by 10⁻⁶°C.⁻¹ at most.

According to one particular embodiment of the invention, this linearthermal expansion coefficient is of the order of 8 to 10×10⁻⁶° C.⁻¹.

A material suited to producing rigid elements according to the inventionmay be chosen from a wide range of materials, particularly metals,ceramics or other inorganic materials, and composites.

For cost reasons in particular, it is preferable to produce the rigidelements based on glass, particularly in the form of plastic and glass,for example glass fiber, composites. The rigid element has advantageousmechanical behavior when the composite contains at least 60% by volumeof glass, preferably at least 75%, particularly at least 80%, especiallyof the order of 90% glass by volume. The highest values just mentionedare recommended when the glazed element is made of glass, whereas whenit is made of polycarbonate or the equivalent, proportions by volume ofat least 60%, preferably at least 75%, of glass are more appropriate.

Glass is a material which is practical to use because it introduces noproblem of affinity with respect to the organic materials that may beused to form the overmolded part which are already selected for theircompatibility with glass. For example, incorporating such a rigidelement into an overmolded part made of polyurethane poses no problem ofintegrity of the composite.

Thanks to the quality of the bond between the rigid element and theovermolded plastic, the final glazing has mechanical performancecomparable to that of glazing reinforced with a metal element, and thisis true even if the rigid glass element has intrinsic mechanicalperformance that is inferior to that of a metal element.

A rigid element according to the invention may thus advantageously becharacterized by a bending strength, which varies according to thegeometry of the element, which is high enough.

An element based on glass also has the advantage of having a weightwhich is reduced by the order of 30 to 50% by comparison with a rigidmetal element. This may be advantageous when the overmolded plastic ismore expensive than the material of which the rigid element is made, anincrease in the volume of the rigid element giving rise to acorresponding saving in material that is to be overmolded.

Finally, the manufacture of the overmolded glazing is made easier with arigid element based on glass for which part of this element can beallowed to come into contact with the glass element in the mold, whereasin the case of a metal rigid element, special precautions need to betaken to prevent any glass-to-metal contact. This is because contactbetween a rigid element based on glass and the surface of the glassglazed element, or the lacquer, if any, covering it, is far less likelyto damage these than contact with a metal rigid element.

According to an advantageous feature, said rigid element is a plasticand glass fiber composite. Such a composite can be obtained by anytechnique known per se for the manufacture of composites, for example bythermoforming (particularly thermocompression) of prepregs.

It is most especially preferable to make the elements from a productconsisting of commingled filaments of glass and of organicthermoplastic, available under the tradename Twintex® from VetrotexSaint-Gobain. The structure and manufacture of these commingledfilaments are described in particular in documents FR 2 516 441, FR 2638 467 and EP 0 599 695.

The manufacture of the rigid elements according to the invention may inparticular call for loose commingled filaments or semi-finished productsin the form of strips or mats consisting of woven or nonwoven commingledfilaments that may possibly be associated with an organic thermoplasticor thermoset. The weaving of the filaments and/or their orientation inone or more favored directions may be selected in a well known way witha view to obtaining desired mechanical properties in given directions.

By way of organic substances that can be used to form a composite rigidelement according to the invention, mention may in particular by made ofpolyolefins such as polyethylene or polypropylene, and of polyesterssuch as polyethylene terephthalate or polybutylene terephthalate.

These same plastics can be used in the composition of commingledfilaments. When a product based on commingled filaments is combined witha plastic, use is advantageously made of a material of the same familyas the one present in said filaments, and preferably exactly the samematerial. These plastics are selected as appropriate for theircompatibility with the glazed element when the latter is itself made ofplastic: to do this they may consist of the same plastic or of amaterial which is inert toward the material of the glazed element (whichis generally the case with polypropylene for example).

Given the weight saving allowed by the use of a rigid element based onglass, this element can be manufactured with at least one dimension, letus say the thickness, that is large enough to allow all types of fixingof various elements to the glazing, particularly by means of a simpleuntapped hole which may take a screw or a force-fitting, snap-fasteningor other means of connection. The rigid element, which may or may not beinserted in an overmolded plastic, may be made of a material of theTwintex® type, in any shape (lug, etc.) suited to fixing or some otherfunction.

Thus, the invention applies amongst other things to the incorporationinto fixed glazing of a fixing support, of a closure mechanism support,and to the incorporation into moving glazing of means of guiding orsupports of means of guiding the glazing. The invention also allows anelectric wires or electric sensors support to be incorporated, withoutthe fear of a short circuit which is ever present with a metal supportelement.

The invention also applies to the addition of reinforcing elements toall types of glazing, particularly opening glazing such as sunroofs oropening backlights made of toughened glass or laminated glass for motorvehicles, or non-opening glazing such as glazed sunroofs bonded to thebodywork of a vehicle, the span of which generally entails reinforcingthe central part in particular. The rigid element or elements thenconstitute a longitudinal reinforcing beam or transverse reinforcinghoop, possibly combined with an overmolded plastic into which they areincorporated.

According to yet another alternative form of the invention, theinvention applies in particular to sunroofs or backlights which open,made of glass, which are laminated, or made of unhardened glass, oralternatively made of plastic, for motor vehicles or for applicationspertaining to buildings.

Of course, this alternative form may also be applied to substrates madeof hardened, toughened glass.

These various glass or plastic substrates are provided on one of theirsides, or are associated, with at least one electrochemical device,particularly an electrically operable system with variable opticaland/or energy properties, this electrochemical device, commonly known aselectrochromic device, being of the type described in WO 00/71777 or inWO 00/57243, for example belonging to the same Applicant.

The use of such glazing or of such a substrate is advantageous inelectrochromic windows, for buildings, particularly for external glazingor for internal partitions or for glazed doors or for roofs, or forlocomotive means of the train, airplane (side window) or automobile(roof, backlight, etc.) type.

The invention may also apply to the incorporation of a reinforcingelement into an overmolded accessory, particularly a spoiler attached tothe backlight of a vehicle.

The glazing equipped according to the invention may just as easily beglazing for a building, glazing for self-propelled or towed terrestrialmotor vehicles such as camping trailers, and for various leisurevehicles, particularly boats etc.

The addition of rigid elements according to the invention mayadvantageously be performed during the operation of molding theovermolded part, but may also be performed simply by bonding onto theovermolded part.

BRIEF DESCRIPTION OF THE DRAWINGS

Other details and features of the invention will become apparent fromthe detailed description which will follow, given with reference to theappended drawings in which:

FIG. 1 depicts a perspective view of glazing according to the invention;

FIGS. 2 and 3 depict views in section of the glazing of FIG. 1 on II-IIand III-III respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is specified for clarity that the various elements of the objectsdepicted are not necessarily drawn to scale.

The glazing of FIG. 1 is a glazed opening sunroof 1 which comprises aglass element 2, particularly made of toughened glass, provided with anovermolded surround 3 made of any suitable plastic, particularly ofpolyurethane.

The surround 3 is deposited on a layer 4 of opaque enamel at theperiphery of the glass element, and the function of which is to concealfrom sight from the outside equipment associated with the glazing.

The surround 3 here runs all the way around the glass element 2, but itmust be understood that, as required, it may extend over just part ofthe periphery thereof.

The surround 3 is in contact with the edge of the glass element and theface of the glass element which will face toward the inside of thevehicle. This allows the opening sunroof 1 to lie flush with thesurrounding bodywork.

As an alternative, the surround 3 could be in contact only with theinterior face of the glass element 2 or be placed straddling the borderof the glass element 2 in contact with both the interior and theexterior faces of the glass element 2.

In FIG. 2, it can be seen that the surround 3 is reinforced along a longside by a reinforcing element 5 which is incorporated into the material3 of the surround.

The reinforcing element is a glass fiber and plastic composite. It ismade, on the one hand, of mats 6 of Twintex® filaments which arecommingled filaments of glass and of thermoplastic (in a ratio by volumeat least equal to 60/40, preferably to 75/25 and at most equal to90/10), woven and/or nonwoven, of a thickness of 3 to 20 mm and, on theother hand, of a thermoplastic 7 identical to or different from the onepresent in the commingled filaments and molded into contact with themats 6. The mats 6 may be shaped by thermoforming prior to the injectionof the material 7 into the mold.

The proportions of the mats 6 and of the plastic 7 are such that thecontent by volume of glass fiber in the composite reinforcing element 5is between 60 and 90%. The addition of thermoplastic 7 is optional; theamount added is adjusted as appropriate according to the volumes andsections that are to be obtained.

The linear thermal expansion coefficient of the rigid element accordingto the invention can be adjusted and mechanical properties equivalent tothose of a metal rigid element, which is heavier by 30 to 50%, forvarying geometries of the rigid element, can be obtained by adapting theshape, by adjusting the proportion of commingled filaments and, withinthis, the proportion of glass fibers, or by superposing several plies ofTwintex® etc.

In FIG. 3, it can be seen that another rigid element 8 is incorporatedinto the surround 3 along a short side. This element 8 serves, on theone hand, to reinforce the glazing and, on the other hand, to attach aroof driving mechanism, not depicted.

The element 8 is made up, in a similar way to the element 5, of mats 9of commingled filaments of glass and of thermoplastic incorporated intoa thermoplastic or thermoset, the materials being identical to ordifferent from those mentioned in respect of the element 5.

An untapped hole 10 is made in a wing of the element 8 to take a partfor fixing the mechanism for driving the roof 1.

The rigid elements 5, 8 may be incorporated into the surround 3 at thetime that the surround 3 is overmolded onto the glass element 2, byplacing them as inserts into the mold, then by injecting the plastic ofthe surround 3.

During this molding operation, the rigid elements inserted into the moldexperience, at the molding temperature, have a thermal expansion on thesame order as the glass element 2, which means that no differentialexpansion stresses occur upon cooling.

As an alternative, at least one of the elements 5, 8 could be bonded tothe surround 3 or fixed to it in some other way with the resultantadvantage of the disappearance of the differential expansion stressesfollowing the heating/cooling cycles experienced by the glazingthroughout its life.

The invention, which has just been described in the particular case ofmoving glazing for a motor vehicle, is not in any way limited to thisembodiment, and encompasses a whole spectrum of variants, particularlyas regards the materials used, the configurations of the glazingelements and the systems used for mounting the glazing.

1. A glazing comprising: a glazed element with an overmolded plasticpart; and at least one rigid element linked to the glazed element,wherein the glazed element comprises a single sheet with an uppersurface, a lower surface and an edge portion therebetween, wherein theat least one rigid element includes glass and has a linear thermalexpansion coefficient differing by 10⁻⁶° C.⁻¹ at most from that of theglazed element, wherein a surround member which extends oversubstantially the entire periphery of said at least one rigid elementand which interconnects said at least one rigid element with a sidesurface of said at least one glazed element, wherein the surround memberconfines the glazed element exclusively via the lower surface and edgeportion of the glazed element, and wherein the at least one rigidelement includes a first portion and a second portion, a first end ofthe first portion is joined to a first end of the second portion so asto provide an acute angle between the first end of the first portion andthe first end of the second portion, a second end of the first portion,opposite the first end of the first portion, and a second end of thesecond portion, opposite the first end of the first portion, are free,wherein a thermoplastic is molded into contact with a first face of thefirst portion and a first face of the second portion, and wherein asecond face of the first portion, opposite the first face of the firstportion, and a second face of the second portion, opposite the firstface of the second portion, contact the surround member.
 2. The glazingas claimed in claim 1, wherein the at least one rigid element isincorporated into the overmolded plastic part.
 3. The glazing as claimedin claim 1, wherein the at least one rigid element has a linear thermalexpansion coefficient of the order of 8 to 10×10⁻⁶° C.⁻¹.
 4. The glazingas claimed in claim 1, wherein the at least one rigid element containsat least 60% by volume of glass.
 5. The glazing as claimed in claim 1,wherein the at least one rigid element contains at most 90% by volume ofglass.
 6. The glazing as claimed in claim 1, wherein the at least onerigid element comprises a plastic and glass fiber composite.
 7. Theglazing as claimed in claim 6, wherein the composite of the at least onerigid element includes a product comprising commingled filaments ofglass and of organic thermoplastic.
 8. The glazing as claimed in claim7, wherein the composite of the at least one rigid element includesloose commingled filaments or semi-finished products in a form of stripsor mats consisting of commingled woven or nonwoven filaments.
 9. Theglazing as claimed in claim 7, wherein the composite of the at least onerigid element includes loose commingled filaments or semi-finishedproducts associated with an organic thermoplastic or thermoset.
 10. Theglazing as claimed in claim 6, wherein the composite of the at least onerigid element comprises a plastic that includes polyolefins orpolyesters.
 11. The glazing as claimed in claim 1, wherein the at leastone rigid element is a reinforcing element.
 12. The glazing as claimedin claim 1, wherein the glazed element includes an electrochemicaldevice, with at least one of variable optical or energy properties. 13.An electrochromic window which includes the glazing as claimed in claim12.
 14. The glazing as claimed in claim 1, wherein said surround memberextends over the entire periphery of said at least one rigid element.15. A glazing comprising: a glass element formed of one of a glasselement consisting of one or more sheets of glass bonded together byadhesive interlayers; and at least one rigid element overmolded on theglass element, wherein said at least one rigid element is incorporatedinto an overmolded plastic part, said at least one rigid element havinga linear thermal coefficient differing by not greater than 10⁻⁶° C.⁻¹from that of the glass element, and wherein said at least one rigidelement comprises glass; and a surround member which extends oversubstantially the entire periphery of said at least one rigid elementand which interconnects said at least one rigid element with a sidesurface of said at least one glazed element, wherein said surroundmember confines the glazed element exclusively via a lower surface andan edge portion of said glass element, wherein the at least one rigidelement includes a first portion and a second portion, a first end ofthe first portion is joined to a first end of the second portion so asto provide an acute angle between the first end of the first portion andthe first end of the second portion, a second end of the first portion,opposite the first end of the first portion, and a second end of thesecond portion, opposite the first end of the first portion, are free,wherein a thermoplastic is molded into contact with a first face of thefirst portion and a first face of the second portion, and wherein asecond face of the first portion, opposite the first face of the firstportion, and a second face of the second portion, opposite the firstface of the second portion, contact the surround member.
 16. The glazingas claimed in claim 1, wherein the overmolded plastic part hasincorporated therein said at least one rigid element.
 17. The glazing asclaimed in claim 15, which comprises an enamel layer positioned betweenthe lower surface of said single sheet and said overmolded plastic part.18. The glazing as claimed in claim 1, wherein the glazed element isfree of recesses.
 19. The glazing as claimed in claim 1, wherein aportion of the glazed element in contact with the surround member islonger than the at least one rigid element.
 20. The glazing as claimedin claim 15, wherein a portion of said glass element in contact withsaid surround member is longer than said at least one element.
 21. Theglazing as claimed in claim 1, wherein an enamel layer is positionedbetween the lower surface of the glazed element and the surround member.